1. Field of the Invention
The present invention relates to a biodegradable polyurethane plastic. More particularly, the present invention relates to a biodegradable polyurethane plastic including phosphorus pentoxide, in which the polyurethane is decomposed biologically by phosphorus pentoxide.
2. Description of the Related Art
It is known that plastics, which have become necessities of modern life due to their convenience, barely decompose in a state of nature and even if they do so it takes several hundred years. In recent years, sea pollution attributable to plastics discharged into the sea, the disposal of plastic waste stemming from the increase in the amount of plastic waste, and the like have become environmental issues. For this reason, degradable plastics have lately attracted considerable attention as an alternative to their disposal. Currently, degradable plastics largely include two kinds of degradable plastics which are photodegradable plastics that are decomposed by light (chiefly ultraviolet) and biodegradable plastics that are decomposed by microbes.
Biodegradable plastics are classified into plastics (biological plastics) produced by microbes, plastics made of natural materials such as starch, cellulose and the like, and chemical synthetic plastics imparted with degradability. When these biodegradable plastics are buried in the ground or discharged into the sea, they are decomposed into low-molecular compounds by microbes existing in nature, such as bacteria, algae, molds and the like, and are then converted into water and carbon dioxide gas or water and methane gas. However, conventional biodegradable plastics are problematic in that they cannot be easily molded, and their molded products have poor physical properties, thus decreasing practicality.
Meanwhile, generally, polyurethane, which is a general term for polymer compounds having a urethane bond (—NHCOO—) in a repeating unit of a main chain thereof, has excellent resistance to aging and stability to oxygen as well as high resistance to chemicals and solvents. Therefore, polyurethane is generally used in the form of polyurethane foam, polyurethane rubber, adhesives, synthetic fibers, paint or the like, and may be used to manufacture plastics. Generally, polyurethane itself has decomposition characteristics such as hydrolyzability, biodegradability and the like. However, polyurethane is problematic in that, since its deposition characteristics are very weak, when polyurethane products are used and then discarded, they are partially decomposed, not completely decomposed, so that they semi-permanently exist or it takes a long period of time for them to completely decompose, thereby causing environment pollution. For this reason, a method of recycling polyurethane products and a method of incinerating polyurethane products are being practically used. However, the method of incinerating polyurethane products is problematic in that harmful materials are generated, and the method of recycling polyurethane products is problematic in that it is difficult to collect waste polyurethane products, and even after they are collected, impurities must be removed from the waste polyurethane products. Therefore, it has been increasingly required to develop polyurethane which can be rapidly decomposed and whose properties do not change. According to this requirement, research into manufacturing polyurethane having excellent degradability has been conducted in various manners. However, in spite of such research, conventional biodegradable polyurethane is problematic in that it decomposes slowly and its properties are rapidly deteriorated at room temperature.
Therefore, a need exists for a system and method for performing a self diagnosis of a device without the inconvenience caused when manually selecting a self diagnosis item from a computer or a user interface.